Cover the film with warm towel for a while. It will be easier to remove.
Scrubing it using hot water with washing powder.
It is pretty annoying. You can try to heat it with electric hair drier and then tear it off.
The reason why you can't remove it may be the glue remains on it. You can try to clean it up with organic solvent. But it takes time, I suppose.
1.Grind the film off using polishing machine. 2. Heating it with electric hair drier and scratching it off. 3. Pouring some boiling water on it and then scratching it off.
